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Chapter 14: Genetic Engineering -Modification of the DNA of an organism to produce new genes with new characteristics.

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Presentation on theme: "Chapter 14: Genetic Engineering -Modification of the DNA of an organism to produce new genes with new characteristics."— Presentation transcript:

1 Chapter 14: Genetic Engineering -Modification of the DNA of an organism to produce new genes with new characteristics

2 Biotechnology Use of organisms to benefit humanity

3 Recombinant DNA technology DNA from different organisms is spliced together Allows scientists to make many copies of any DNA segment (clone) Can introduce foreign DNA into cells of microorganisms

4 Recombinant DNA technology Restriction enzymes – cut DNA – Bacteria produce for defense against viruses Vector – transports DNA into a cell – Ex: bacteriophage – Plasmid – separate, smaller circular DNA that maybe be present and able to replicate inside bacteria Transformation – uptake of foreign DNA by cells – How plasmids can get into bacteria

5 Bacterial Conjugation and Recombination

6 Recombinant DNA technology Palindromic sequences – reads the same as complement, in opposite direction – AAGCTT – TTCGAA – Many restriction enzymes cut these sequences Restriction enzymes cut on a stagger  sticky ends (can pair with complementary single- stranded end of other DNA cut with same enzyme) DNA Ligase – links 2 fragments  recombinant DNA

7 Fig Restriction site DNA Sticky end Restriction enzyme cuts sugar-phosphate backbones One possible combination Recombinant DNA molecule DNA ligase seals strands. 3 DNA fragment added from another molecule cut by same enzyme. Base pairing occurs. 2

8 Restriction Enzymes

9 Steps of Creating a Recombinant DNA Plasmid (Basic) 1. Plasmids and desired DNA cut by same restriction enzyme 2. Mix 2 types of DNA so sticky ends pair 3. DNA ligase forms bonds between fragments


11 Fig DNA of chromosome Cell containing gene of interest Gene inserted into plasmid Plasmid put into bacterial cell Recombinant DNA ( plasmid ) Recombinant bacterium Bacterial chromosome Bacterium Gene of interest Host cell grown in culture to form a clone of cells containing the “cloned” gene of interest Plasmid Gene of Interest Protein expressed by gene of interest Basic research and various applications Copies of gene Protein harvested Basic research on gene Basic research on protein Gene for pest resistance inserted into plants Gene used to alter bacteria for cleaning up toxic waste Protein dissolves blood clots in heart attack therapy Human growth hor- mone treats stunted growth

12 Cloning a Gene

13 Fig Bacterial cell Bacterial plasmid lacZ gene Hummingbird cell Gene of interest Hummingbird DNA fragments Restriction site Sticky ends amp R gene TECHNIQUE Recombinant plasmids Nonrecombinant plasmid Bacteria carrying plasmids RESULTS Colony carrying non- recombinant plasmid with intact lacZ gene One of many bacterial clones Colony carrying recombinant plasmid with disrupted lacZ gene

14 Cloning DNA Genome – total DNA per cell Genomic library – collection of DNA fragments more or less representative of all DNA in genome Genetic Probe – single stranded DNA or RNA that is radioactively labeled and can attach to target sequence by base pairing rules

15 A probe can be synthesized that is complementary to the gene of interest For example, if the desired gene is – Then we would synthesize this probe G 5 3 …… GGCCCTTTAAA C 3 5 CCGGGAAATTT

16 DNA Probe

17 Using a DNA probe

18 Polymerase Chain Reaction (PCR) Can amplify a small sample of DNA quickly DNA replication in vitro 2 strands separated by heating so special heat-resistant DNA polymerase called Taq polymerase used (thermophile) MAJOR BONUS: Only specific sequences can be replicated Study: crime scenes, archaeological remains

19 PCR

20 Gel Electrophoresis Separates fragments like DNA, RNA or polypeptides (they carry charge and can migrate in an electrical field RNA and DNA (-) --- so they move to (+) pole Smaller fragments go further Compare sample to standard Usually “blot” - transfer DNA from gel to nitrocellulose filter for further analysis DNA Fingerprinting

21 Gel Electrophoresis

22 Fig. 20-9a Mixture of DNA mol- ecules of different sizes Power source Longer molecules Shorter molecules Gel Anode Cathode TECHNIQUE 1 2 Power source – + + –

23 Fig. 20-9b RESULTS




27 DNA Fingerprint

28 Transgenic Organisms Plants and animals in which foreign genes have been incorporated Animals – Inject DNA into nucleus of egg or stem cell – Eggs implanted in uterus; stem cells injected into blastocysts + then implanted into foster mother Plants – Disease resistance – Pesticide resistance

29 Transgenics

30 Fig Cultured stem cells Early human embryo at blastocyst stage (mammalian equiva- lent of blastula) Different culture conditions Different types of differentiated cells Blood cells Nerve cells Liver cells Cells generating all embryonic cell types Adult stem cells Cells generating some cell types Embryonic stem cells From bone marrow in this example

31 Fig TECHNIQUE Mammary cell donor RESULTS Surrogate mother Nucleus from mammary cell Cultured mammary cells Implanted in uterus of a third sheep Early embryo Nucleus removed Egg cell donor Embryonic development Lamb (“Dolly”) genetically identical to mammary cell donor Egg cell from ovary Cells fused Grown in culture

32 Fig

33 Cloning Video

34 GE Plants

35 Application of GE Human proteins – Insulin – Hormones - HGH Human treatments for disease – Multiple sclerosis, certain cancers, heart attacks, forms of anemia Vaccines

36 Fig

37 Fig This photo shows Earl Washington just before his release in 2001, after 17 years in prison. These and other STR data exonerated Washington and led Tinsley to plead guilty to the murder. (a) Semen on victim Earl Washington Source of sample Kenneth Tinsley STR marker 1 STR marker 2 STR marker 3 (b) 17, 19 16, 18 17, 19 13, 1612, 12 14, 1511, 12 13, 1612, 12

38 Forensics

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